/*
 * Copyright (c) OSGi Alliance (2011). All Rights Reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.osgi.service.component.annotations;

/**
 * Cardinality for the {@link Reference} annotation.
 * 
 * <p>
 * Specifies if the reference is optional and if the component implementation
 * support a single bound service or multiple bound services.
 * 
 * @version $Id$
 */
public enum ReferenceCardinality {
	/**
	 * The reference is optional and unary. That is, the reference has a
	 * cardinality of {@code 0..1}.
	 */
	OPTIONAL, // 0..1
	/**
	 * The reference is mandatory and unary. That is, the reference has a
	 * cardinality of {@code 1..1}.
	 */
	MANDATORY, // 1..1
	/**
	 * The reference is optional and multiple. That is, the reference has a
	 * cardinality of {@code 0..n}.
	 */
	MULTIPLE, // 0..n
	/**
	 * The reference is mandatory and multiple. That is, the reference has a
	 * cardinality of {@code 1..n}.
	 */
	AT_LEAST_ONE; // 1..n
}